> smtpd has been removed according to the schedule in PEP 594

Damn! I guess it's time to cross out my snippet of running a debug smtp server in almost any Linux distro & Mac:

python -m smtpd -n -c DebuggingServer localhost:25

> Remove the distutils package. It was deprecated in Python 3.10 by PEP 632

So apparently we need to replace

from distutils.version import StrictVersion

with

from pkg_resources import parse_version

A bit labor for my code but OK.